Radiology of the head, face and neck is generally done with conventional x-ray equipment in smaller hospitals, however, in larger institutions where more sophisticated techniques and diagnosis are carried out, dedicated equipment is utilized to enable a more precise and repeatable technique to be achieved for the various examinations. Radiographic diagnosis of the head, face and neck presents some unusual problems because of the complexity of the skull and the heavy over layers of bony material that must be penetrated in order to visualize internal parts. In order to achieve proper visualization of certain parts, precise positioning and angulation of the skull with respect to the x-ray machine must be achieved. This is necessary in order to provide the proper view as well as to avoid obstructing irregular bone masses which would obilterate the part to be viewed.
The difficulties encountered in Radiography of the head, face and neck is indicated by the fact that there are six major procedures which are frequently done by tomographic technique because conventional technique frequently does not provide adequately diagnostic information. These techniques are: (1) Inner Ear, (2) Facial Bone, i.e. Orbits, Sinus, (3) Sella Turcica, (4) Odontoid process, (5) entire Cervical Spine, (6) TM Joint. Moreover, the fact that there are a large number of medical sub specialties, each attending to various aspects of the head, face and neck is further indication of the complexity of this region.
In an effort to simplify head, face and neck procedures and to provide maximum precision and repeatabilty, dedicated systems have been designed and marketed. The oldest system is the Franklin Head Unit which has been around for over 30 years and the other system, which is fairly recent, is the Siemens Orbix. The Franklin Head Stand which is utilized extensively because of its' relatively moderate price utilizes an x-ray tube and collimator mounted on a C-arm structure which is then attached to a vertical column. The C-arm structure can travel vertically as well as rotate. To perform a given technique the patient is placed in a roll-around chair, the patient is then rolled into position inside the arm structure, that is, between the x-ray tube, collimator and film tray. He then has his head clamped with the head clamp. The light from the collimator then shines down upon that part of the head to be radiographed after the appropriate angle is indicated on the rotational part of the C-arm. The collimator is then opened to the appropriate aperture. The x-ray is then taken.
This type of positioning has a number of limitations with respect to precision. In addition, the machine is not capable of high resolution magnification work. One of the main difficulties with the machine is that by only being able to utilize the entering ray as simulated by the collimator light a precise angling of the patients head is difficult to determine, that is, there could be a slight rotational effect on the head and this could not be determined with any degree of precision because there is only one degree of freedom with the light. The use of the single light does not permit the use of land marks along the side of the head, such as the line of the inner ear, etc. In addition, the presence of the head clamp which serves to center the head, makes difficult side angle shots of the head and therefore limits the use of the system for many lateral exposures.
To introduce high precision and repeatability as well as enabling more versatility, the Orbix was designed by Siemens. This unit require a dedicated room and is quite expensive, however, it offers great precision in alignment. It is a ceiling mounted unit with precision in all motions. The C-arm unit which is mounted to the main arm can move vertically as well as rotate and the film tray can also move independently. It has two precise location lights which provide orthoginal alignment, one in the collimator and one at the pivot point at right angles to the collimator. The two alignment lights provide cross-hair lighted lines for precise positioning which enables precision motion to be prescribed from any one location to another location. To utilize the Orbix requires a fair amount of calculation work. The Operations Manual provides a series of steps to obtain a precise position. A cursory examination of the Orbix manual illustrates the above.
The precision of the Orbix system is limited by the ability of the operating technician to provide precise initial marks, whether it be a TM joint or otherwise. Typically one might expect precision here of plus and minus several millimeters. The precision of the machine thereafter probably can be measured in fractions of a millimeter, therefore the overall preciseness is operator determined.
It is an object of the present invention to enable precise positioning of the various procedures of the head, face and neck to be achieved.
It is yet another object of the present invention to permit this precise positioning to be done in a simple, repeatable and straight forward fashion.
It is still yet another object of the present invention to enable radiographs to be obtained from any arbitrary angle on the patient by use of a unique radio-transparent head positioning and immobilization device.
It is a further object of the present invention to permit an additional degree of freedom in visualizing the x-ray path than has been heretofore available.
It is yet another object of the present invention to provide a small compact system that may be stored in a corner of a room without requiring large amounts of space.